Virginia’s blue crab season opened strong Monday as watermen returned to Chesapeake Bay docks with bushels full of the normally dormant crustacean.

“This is unprecedented. We’ve never seen it this early,” said Johnny Graham, president of Hampton-based Graham & Rollins Seafood, one of the state’s largest crab processing plants.

The state’s commercial crab season begins every March, but the first few weeks are usually lean because most crabs have not stirred from their winter resting spots at the bay floor. This year is different because warm air temperatures — 3 to 7 degrees above normal since November — kept the bay and its tributaries from getting too cold.

As a result, crabs are seeking food, including bait in crab pots.

“They’ve been up a long time. It’s just been so warm,” said Jimmy Winder, a Poquoson watermen who arrived at Graham & Rollins with a few dozen bushels in the bed of his pickup truck.

Crab processing plants in Newport News, Isle of Wight County, Poquoson, and other areas of the bay also reported strong opening day numbers. Some crabs will be picked and their meat frozen, while others will be sent live to restaurants.

There is some concern, however, that the good times won’t last. Large processors, such as Graham & Rollins, say they struggle to find people willing to perform the tedious and modest-paying task of picking meat from crabs. They say they’re forced to hire migrant workers under the federal H2-B visa program.

Delays in the application process have Graham worried that workers from Mexico won’t arrive until mid-April at best. Meanwhile, he said he does not have enough local workers to meet the demand.

“I’m going to be turning away watermen because I don’t have the workers,” Graham said.

It is the latest problem for the visa program, which connects workers across the United States to labor-intensive, seasonal jobs, such as landscaping and hotel cleaning.

The U.S. Department of Labor, acting on a court order, was set to boost H2-B workers’ wages last year. But members of Congress, including several in Hampton Roads, lobbied against the plan. It was delayed until Oct. 1.

Another Labor Department rule, effective April 23, will require employers to guarantee 75 percent of the employees wages regardless of natural disasters, such as a hurricane, that could affect the fishery.

The Virginia seafood industry annually employs about 1,660 H2-B workers, according to a Virginia Institute of Marine Science report issued last year.

The promising start of the season comes as the bay’s blue crab population continues its rebound after a near collapse. Stung by habitat loss, overfishing and pollution, crabs fell to record low in 2007, when scientists estimated a total 249 million baywide.

Strict harvest limits, including canceling the winter dredge season, helped numbers surge to 658 million in 2010. The population dropped to 460 last spring due to an unusually cold winter. New survey results are expected this spring.

The population rise has coincided with an increases in crab landings. Last year, the baywide harvest was 89 million pounds, the highest level since 1993.